Papers I returned to fool (5)
I believe the answer is:
idiot
'fool' is the definition.
(synonyms)
'papers i returned to' is the wordplay.
'papers' becomes 'ID' (identifying documents are one's 'papers').
'returned' is a reversal indicator.
'to' written backwards gives 'ot'.
'id'+'i'+'ot'='IDIOT'
(Other definitions for idiot that I've seen before include "Blockhead" , "Ass, nincompoop" , "Village character" , "The - (Dostoievsky)" , "Charlie" .)